The aims of this study are to: 1. collect diagnostic, enzyme and genetic markers from family members of patients with bipolar and unipolar affective disorders and 2. analyze these data statistically to determine if among these presumed risk factors, one can identify high-risk individuals, delineate a clear mode of genetic transmission for these disorders, and finally establish genetic linkage between affective illness and known genetic markers. Patients are those attending the Lithium Clinic of the New York State Psychiatric Institute, the Columbia Depression Research Program and the Foundation for Depression and Manic-depression, Inc. All patients and relatives are interviewed with the structured interview, the Schedule for Affective Disorders and Schizophrenia (SADS). Analysis of blood samples for genetic markers are done at the Genetics Laboratory of the University of North Carolina.